----- Original Message -----

From:

[email protected]

To:

<[email protected]>

Cc:

Sent:

Sun, 29 Jul 2018 23:57:39 -0700

Subject:

[BITX20] Gamma-matching antenna tuner

Hi, all.

?

I am getting interested in a Gamma-Matching antenna tuner (manual one) for suppressing spurious in order to observe Japan’s new spurious regulation.

?

BPF will be fine but I need to make number of coils, right?

?

Then, can anyone point me out where I find some schematics of the Gamma-Matching tuner, or kit of it is very much appreciated.

?

Thanks in advance.

?

// hiro, JJ1FXF

Hiro,? suggest you look at? ARRL antenna HB . You should be able to find some PDF on line .....copyright breach and all. (this was supposed to be a? PM But what the Heck)

Gamma match generally used only on 2m and above. ONe side of your coax goes directly to the driven ele dipole side A.

Other side goes to? a rod that lines away from the side b but? paralled to? it. THis can be a? solid rod or of the same round stock as the driven element.

There are two PE or PP plastic elements holding the rod away from the B side driven element.? The rod can be slid back and forth along the B element? to get the best possible coupling.

THe exact stand off? distance and rod length? are a black art .? You never try to test or tune up this stuff except at low power or reduced V on finals.

THe coupling into the B side is capacitive and inductive? and distributed.? Hence black art.? It is hellish unlikely you will get this to work with anything other than a Yagi antenna.

Do you have a 1:1 balun in line as in current balun. If you have harmonics in your transmitted signal this will help the issue of return down the outside of your coax? and that will help keep any harmonics forced into the antenna where since they are not resonant , will be somewhat suppressed.? ?Voltage baluns can be work of the devil and for VHF accept nothing less than type 61 material in the balun core. Above 150 Mhz you cannot even have type 61 because it is getting very lossy but only your tests with a FSMeter will show what the difference is.

cheers New member -

A and B sides are whatever you define them to be - as above.

?

Timothy E. Fidler : Engineer BE Mech(1) Auckland , NDT specialist AINDT UT /RT3 , MT2 CB #2885,?
Telephone Whangarei?? 022? 691 8405
e: Engstr@...

----- Original Message -----

From:

[email protected]

To:

<[email protected]>

Cc:

Sent:

Sun, 29 Jul 2018 23:57:39 -0700

Subject:

[BITX20] Gamma-matching antenna tuner

Hi, all.

?

I am getting interested in a Gamma-Matching antenna tuner (manual one) for suppressing spurious in order to observe Japan’s new spurious regulation.

?

BPF will be fine but I need to make number of coils, right?

?

Then, can anyone point me out where I find some schematics of the Gamma-Matching tuner, or kit of it is very much appreciated.

?

Thanks in advance.

?

// hiro, JJ1FXF

Hiro san,

A pi type tuner is generally in the same form as Low pass filters.? As such it can help with harmonics
but lower frequency spurious outputs it will be less helpful.

What you likely want is a transmitting band pass filter then an antenna matcher after that.
Two sites that may be more helpful.??





Allison

There are a great many articles available on-line for Gama Match Antenna.

Do a Google search for "" to see what is available.?

Arv? K7HKL
_._

On Mon, Jul 30, 2018 at 2:08 AM Timothy Fidler <engstr@...> wrote:

Hiro,? suggest you look at? ARRL antenna HB . You should be able to find some PDF on line .....copyright breach and all. (this was supposed to be a? PM But what the Heck)

Gamma match generally used only on 2m and above. ONe side of your coax goes directly to the driven ele dipole side A.

Other side goes to? a rod that lines away from the side b but? paralled to? it. THis can be a? solid rod or of the same round stock as the driven element.

There are two PE or PP plastic elements holding the rod away from the B side driven element.? The rod can be slid back and forth along the B element? to get the best possible coupling.

THe exact stand off? distance and rod length? are a black art .? You never try to test or tune up this stuff except at low power or reduced V on finals.

THe coupling into the B side is capacitive and inductive? and distributed.? Hence black art.? It is hellish unlikely you will get this to work with anything other than a Yagi antenna.

Do you have a 1:1 balun in line as in current balun. If you have harmonics in your transmitted signal this will help the issue of return down the outside of your coax? and that will help keep any harmonics forced into the antenna where since they are not resonant , will be somewhat suppressed.? ?Voltage baluns can be work of the devil and for VHF accept nothing less than type 61 material in the balun core. Above 150 Mhz you cannot even have type 61 because it is getting very lossy but only your tests with a FSMeter will show what the difference is.

cheers New member -

A and B sides are whatever you define them to be - as above.

?

Timothy E. Fidler : Engineer BE Mech(1) Auckland , NDT specialist AINDT UT /RT3 , MT2 CB #2885,?
Telephone Whangarei?? 022? 691 8405
e: Engstr@...

----- Original Message -----

From:

[email protected]

To:

<[email protected]>

Cc:

Sent:

Sun, 29 Jul 2018 23:57:39 -0700

Subject:

[BITX20] Gamma-matching antenna tuner

Hi, all.

?

I am getting interested in a Gamma-Matching antenna tuner (manual one) for suppressing spurious in order to observe Japan’s new spurious regulation.

?

BPF will be fine but I need to make number of coils, right?

?

Then, can anyone point me out where I find some schematics of the Gamma-Matching tuner, or kit of it is very much appreciated.

?

Thanks in advance.

?

// hiro, JJ1FXF

I don't think you will be imprisoned for a long time because of the spurs and the harmonics of the Ubitx unless, as Allison pointed out elsewhere, you use the ssb mode above 20Mhz.

Il 31/lug/2018 00:20, "hirosmb" <hirosmb@...> ha scritto:

Allison-san,

Thanks a lot for your info.

I am checking those presented URLs and a bit surprised with a huge filter using PC case. :)

In my understanding, because uBitx uses DDS and so is not likely to produce lower harmonics such as by frequency multiplier, but higher harmonics may occur in most cases.

Also I am afraid that the fixed BPF or LPF (such as until 30MHz) may not suppress the second harmonics (14MHz) when emitting 7MHz CW, but hoping that the pi-match antenna tuner may work for this case.

// hiro, JJ1FXF

2018/07/31 0:07、ajparent1/KB1GMX <kb1gmx@...&驳迟;のメール:

Hiro san,

A pi type tuner is generally in the same form as Low pass filters.? As such it can help with harmonics
but lower frequency spurious outputs it will be less helpful.

What you likely want is a transmitting band pass filter then an antenna matcher after that.
Two sites that may be more helpful.??





Allison

Hiro san,

The NCO (form of synthesis) is very clean save for harmonics due to square waveform.

However there are three oscillators and mixers and the resulting combines can and do
create spurs.

Allison

Would they not just need band pass filters for whatever the desired band is? I kind of see where you might be able to suppress spurious emissions in a tuner, but why? My limited understanding is that the ubitx has filters for hf bands 20 meters and lower. Do they not provide enough suppression?? If not a filter should be pretty straight forward to construct. No?

Christopher,

I saw somewhere that spurious emission is at the level of -45dB toward the fundamental frequency.

However, Japan’s latest spurious regulation requires more than -50dB and so I started thinking about pi-match tuner or BPF.

This doesn’t mean that uBitx doesn’t suppress good enough spur but it just means that Japan’s regulation is a little tight, I suppose.

// hiro, JJ1FXF

2018/07/31 5:14、Christopher Miller <djmalak2k6@...&驳迟;のメール:

Would they not just need band pass filters for whatever the desired band is? I kind of see where you might be able to suppress spurious emissions in a tuner, but why? My limited understanding is that the ubitx has filters for hf bands 20 meters and lower. Do they not provide enough suppression?? If not a filter should be pretty straight forward to construct. No?